Makindo Medical Notes

Metastatic adenocarcinoma is a relatively common problem, where cancer cells spread from a primary site to distant organs. Possible primary sources include:

Common Primary Sources of Metastatic Adenocarcinoma

• Lung: The lung is a frequent site of primary adenocarcinoma, which can metastasize to the liver, bones, brain, and adrenal glands.
• Thyroid: Papillary and follicular thyroid cancers, which are types of adenocarcinomas, can spread to the lungs and bones.
• Gut: Adenocarcinoma can arise in the gastrointestinal tract, including the lower oesophagus (often associated with Barrett’s oesophagus), stomach, and colorectal areas. These cancers frequently metastasize to the liver and peritoneum.
• Ovarian and Uterine: Ovarian and endometrial adenocarcinomas can spread locally to the peritoneum and distally to the lungs, liver, and lymph nodes.
• Pancreas: Pancreatic adenocarcinoma commonly spreads to the liver and peritoneum. It's often diagnosed at a late stage due to its aggressive nature.
• Breast: Breast adenocarcinomas (ductal and lobular) are among the most common cancers in women, often spreading to the bones, liver, lungs, and brain.
• Adrenal and Parathyroid: Adrenocortical and parathyroid adenocarcinomas are rare but can metastasize to distant sites, including bones, lungs, and liver.
• Renal (Kidney): Renal cell carcinoma, though not a classic adenocarcinoma, is often categorized as such and can metastasize to the lungs, bones, liver, and brain.

Adenocarcinomas originate in glandular tissue and account for a large portion of metastatic cancers. They can spread via the bloodstream or lymphatic system, infiltrating distant organs and causing secondary tumours. Metastasis can complicate treatment and prognosis, making early detection crucial.

Common Cancers That Are Not Adenocarcinoma

• Bladder - Transitional Cell Carcinoma: Bladder cancer is typically transitional cell carcinoma (TCC), arising from the urothelium. It's not classified as adenocarcinoma, though rare cases of bladder adenocarcinoma exist.
• Larynx - Squamous Cell Carcinoma: Most cancers of the larynx are squamous cell carcinomas (SCC), not adenocarcinomas. These are typically linked to smoking and alcohol use.
• Cervix - Squamous Cell Carcinoma: The majority of cervical cancers are squamous cell carcinomas, though adenocarcinomas can occur. Squamous cell carcinomas often result from HPV infection.

Diagnostic Approach for Metastatic Adenocarcinoma

• Histopathological Examination: The diagnosis of metastatic adenocarcinoma is usually confirmed by biopsy and histological examination, with immunohistochemical staining to identify the tissue of origin.
• Imaging: CT scans, MRIs, and PET scans are commonly used to identify metastases and evaluate the extent of the disease.
• Blood Tests: Tumor markers like CA-125 (for ovarian cancer) and CEA (for colorectal cancer) can be useful in identifying specific adenocarcinomas.

Treatment Options for Metastatic Adenocarcinoma

• Surgical Resection: Surgery may be an option for localized metastases in some cases, though it is less common when cancer has spread widely.
• Chemotherapy: Systemic chemotherapy is a cornerstone treatment, particularly for metastatic disease. It aims to shrink tumours and slow disease progression.
• Targeted Therapy: Drugs that specifically target cancer cell receptors or signaling pathways (e.g., EGFR inhibitors in lung cancer) have improved outcomes in certain adenocarcinomas.
• Radiation Therapy: Radiation can be used to control local tumour growth or palliate symptoms in cases of bone or brain metastases.
• Immunotherapy: In recent years, immunotherapy has shown promise, especially in certain types of adenocarcinomas like lung and colorectal cancers.

Metastatic adenocarcinoma poses significant challenges in terms of diagnosis and treatment, but advances in imaging, pathology, and therapies have improved survival rates for many types. Early detection and a multidisciplinary approach are essential for improving outcomes.